James Allen Bertelsen (born February 26, 1950) is a former American football player. He played professionally as a running back for five seasons in the National Football League (NFL) with the Los Angeles Rams. He played college football at the University of Texas at Austin and was a highly-regarded high school football player in Wisconsin out of Hudson.
As a sophomore at Texas in 1969, he helped lead the Longhorns to a national championship in the Wishbone option offense, alongside James Street, Steve Worster, and Ted Koy.As a senior in 1971, Bertlesen was the team's lead ground gainer. In his career at Texas (1969–1971), he rushed for 2,510 yards, averaging 6.1 yards a carry and 33 touchdowns, and also had nine 100-yard rushing games.
Bertelsen was selected in the second round of the 1972 NFL Draft, thirtieth overall, by the Los Angeles Rams. He averaged four yards per carry as a pro, and rushed for 854 yards in 1973.After his NFL career, Bertelsen returned to the Austin area.